Semiconductor device manufacturing method and ring-shaped reinforcing member

ABSTRACT

A ring-shaped reinforcing ring ( 13 ) formed of, for example, silicon, is adhered to one surface of a thinly processed semiconductor substrate ( 11 ). The reinforcing ring ( 13 ) is adhered thereto with an organic adhering material layer ( 14 ) formed of a metal or alloy with a relatively low melting point or polyimide resin with a relatively low melting point or softening point. Forming a metallic film ( 15 ) is executed in a state that the reinforcing ring ( 13 ) is adhered to the semiconductor substrate ( 11 ). The reinforcing ring ( 13 ) has the same outer diameter as that of the semiconductor substrate ( 11 ). Moreover, since a total thickness of the thinly processed semiconductor substrate ( 11 ) and the reinforcing ring ( 13 ) is substantially equal to that of the semiconductor substrate ( 11 ) which is not thinly processed, the semiconductor substrate ( 11 ) to which the reinforcing ring ( 13 ) is adhered can be transferred by the existing transferring unit.

TECHNICAL FIELD

The present invention relates to a method for manufacturing asemiconductor device having a relatively thin semiconductor substrateand ring-shaped reinforcing member used therein.

BACKGROUND ART

For example, a power semiconductor device such as a power transistor orthe like includes a semiconductor substrate having multiplesemiconductor regions formed thereon and electrodes formed on bothsurfaces of the semiconductor substrate.

Some of power semiconductor devices are miniaturized and thinned inaccordance with miniaturization of electronic equipment. The powersemiconductor devices of this type generally include a relatively thinsemiconductor substrate.

Conventionally, the power semiconductor device having a thinsemiconductor substrate is manufactured by, for example, the followingprocesses.

First of all, as illustrated in FIG. 4A, a semiconductor substrate 100is prepared. In a surface region of one surface of the semiconductorsubstrate 100, multiple semiconductor regions are formed by impuritydiffusion and the like. Multiple semiconductor devices are formed ofthese multiple semiconductor regions. Moreover, on the surface of thesemiconductor substrate 100, electrodes such as an emitter electrode, asource electrode, etc. (not shown) are also formed.

Next, a first reinforcing member 101 is adhered to one surface of thesemiconductor substrate 100 with an organic adhesive (for example,ultraviolet curable resin).

Sequentially, the other surface of the semiconductor substrate 100 iscut or etched to thin the semiconductor substrate 100 as illustrated inFIG. 4B.

When the semiconductor substrate 100 is thinned, intensity of thesemiconductor substrate 100 decreases. For this reason, regarding thesingle use of the semiconductor substrate 100, a nick and a crack easilyoccur on the semiconductor substrate 100 when it is handled ortransferred in the following processes. The first reinforcing member 101prevents occurrence of the nick and the crack on the semiconductorsubstrate 100 and enhances the strength of the semiconductor substrate100 in a state that it is adhered to the semiconductor substrate 100.

After that, a metallic film 102 is formed on the other surface of thesemiconductor device 100 by sputtering, vacuum deposition, etc., asillustrated in FIG. 4. The metallic film 102 is patterned to formelectrodes such a collector electrode, a drain electrode, and the like.

Next, a second reinforcing member 103 to which a ring-shape frame 104 isadhered is adhered to the other surface of the semiconductor substrate100 as illustrated in FIG. 4D. The second reinforcing member 103 fixeseach semiconductor device chip when, for example, the semiconductorsubstrate 100 is diced into the respective chips. After that, the firstreinforcing member 101 is removed from the semiconductor substrate 100.

Sequentially, the semiconductor substrate 100 is divided into multiplesemiconductor device chips 106 by, for example, a dicing cutter 105 asillustrated in FIG. 4E.

Then, the second reinforcing member 103 is removed from eachsemiconductor device chip 106. Accordingly, the semiconductor devicechips 106 are individually separated and sent to a next process such asbonding and the like.

In the aforementioned conventional manufacturing process, the firstreinforcing member 101 is adhered to one surface of the semiconductorsubstrate 100 with the organic adhesive.

However, in this method, there is a case in which components of theorganic adhesive are volatilized when the metallic film 102 is beingformed on the other surface of the semiconductor substrate 100, causingan adverse effect on the formation of the metallic film 102.

For example, when the semiconductor substrate 100 to which the firstreinforcing member 101 is adhered is subjected to sputtering, vacuumdeposition, etc., with a degree of vacuum of about 10⁻⁵ Pa and at atemperature about 100° C. to 200° C., the organic adhesive decomposes togenerate gas. The gas reduces the quality of the metallic film 102.

In order to enhance the strength of the semiconductor substrate 100 andprevent the 10 reduction in the quality of the metallic film 102, it canbe considered that the semiconductor substrate 100 is transferred in astate that the semiconductor substrate 100 is held by a dedicated jig.However, in the case of using the dedicated jig, the existingtransferring unit, cassette, stage, etc., cannot be used, so that a unitfor a manufacturing process must be changed in order to correspond tothe dedicated jig.

As such, it has been difficult to prevent occurrence of the nick and thecrack on the semiconductor substrate, because various problems have beenfound in the prevention process.

The present invention has been made in consideration of theaforementioned circumstances, and an object of the present invention isto provide a semiconductor device manufacturing method that can easilyprevent occurrence of a nick and a crack on a semiconductor substrateand a ring-shaped reinforcing member used therein.

Also, an object of the present invention is to provide a semiconductordevice manufacturing method that can form electrodes with highreliability and a ring-shaped reinforcing member used therein.

Furthermore, an object of the present invention is to provide asemiconductor device manufacturing method that can prevent occurrence ofa nick and a crack on a semiconductor substrate without increasingmanufacturing cost and a ring-shaped reinforcing member used therein.

DISCLOSURE OF INVENTION

In order to achieve the above object, a semiconductor devicemanufacturing method according to a first aspect of the presentinvention includes a first step of preparing a semiconductor substrate(11) on which multiple semiconductor devices are formed and thinning thesemiconductor substrate (11); a second step of adhering a reinforcingmember (13) through which a part of one surface of the semiconductorsubstrate (11) is exposed to the one surface thereof with an adheringmaterial; a third step of forming a metallic film (15) for forming anelectrode provided in the semiconductor device on an exposed portion ofone surface of the semiconductor substrate (11) or the other surface ofthe semiconductor substrate (11); and a fourth step of removing thereinforcing member (13) from the semiconductor substrate (11) and dicingthe semiconductor substrate (11); and wherein the adhering member (13,25) is formed of material whose state changes at temperature higher thana processing temperature in the third step.

In this way, according to this manufacturing method, the ring-shapedreinforcing member is adhered to the semiconductor substrate whosestrength is reduced by thinly processing to prevent occurrence ofoccurrence of the nick and the crack on the semiconductor substrate. Theuse of the ring-shaped reinforcing member with the outer diameter equalto that of the semiconductor substrate eliminates the need for changingthe transferring unit and cassette according to the dedicated jig,unlike the case, for example, in which the dedicated jig for enhancingstrength of the thinly processed semiconductor substrate is used.Moreover, according to this manufacturing method, as an adheringmaterial for adhering the ring-shaped reinforcing member to thesemiconductor substrate, a material is used that does not change itsstate at temperature added thereto when the metallic film is formed. Forthis reason, under the metallic film forming conditions, the adheringmaterial does not generate gas that is due to its melting and thatadversely influences formation of the metallic film. This makes itpossible to form electrodes with high reliability.

The reinforcing member (13) may have an opening at its center and a ringshape with an outer diameter equal to an outer diameter of thesemiconductor substrate (11). And in the second step, the ring-shapedreinforcing member (13) may be adhered to one surface of thesemiconductor substrate (11) by the adhering material in a state that anouter periphery of the reinforcing member (13) is matched with an outerperiphery of the semiconductor substrate (11), In the third step, themetallic film (15) may be formed on one surface of the semiconductorsubstrate (11) which is exposed through the opening of the ring-shapedreinforcing member (13).

The adhering material may be formed of a metal or alloy having a meltingpoint higher than a processing temperature in the third step or heatresistance resin having a melting point or a softening point higher thanthe processing temperature in the third step.

The heat resistance resin may be polyimide resin.

In the second step, the adhering material layer (14, 25) may be formedon one surface of the ring-shaped reinforcing member (13), the surfaceof the ring-shaped reinforcing member (13) may be placed on one surfaceof the semiconductor substrate (11) and the adhering material layer (14,25) disposed between the ring-shaped reinforcing member (13) and thesemiconductor substrate (11) may be melted, and the adhering materiallayer (14, 25) may be hardened by cooling to adhere the ring-shapedreinforcing member (13) to the semiconductor substrate (11).

In the first step, a first tape reinforcing member (12) may be adheredto the other surface of the prepared semiconductor substrate (11) withan organic adhesive and one surface of the semiconductor substrate (11)may be thinly processed in a state that the first tape reinforcingmember (12) is adhered, thereby thinning the semiconductor substrate(11) up to a predetermined thickness; in the second step, thering-shaped reinforcing member (13) may be adhered to one surface of thesemiconductor substrate with the adhering material layer (14) in a statethat the first tape reinforcing member (12) is adhered to the othersurface of the semiconductor substrate (11); and in the third step, themetallic film (15) may be formed on one surface of the semiconductorsubstrate (11) through the opening of the ring-shaped reinforcing member(13) after removing the first reinforcing member (12) from thesemiconductor substrate (11) in a state that the ring-shaped reinforcingmember (13) is adhered to the semiconductor substrate (11).

The adhering material layer (14) may have a melting point lower thanheat resistance temperature of the first tape member (12).

Moreover, in the fourth step, a second tape reinforcing member (18) maybe adhered to the other surface of the semiconductor substrate (11), thering-shaped reinforcing member (13) may be removed from one surface ofthe semiconductor substrate (11), and the semiconductor substrate (11)may be diced into chips (22) that form the respective semiconductordevices.

The adhering material layer (14) may have a melting point lower thanheat resistance temperature of the second tape reinforcing member (18);and the adhering material layer (14) may be melted by heating attemperature lower than heat resistance temperature of the second tapereinforcing member (18), thereby removing the ring-shaped reinforcingmember (13) from the semiconductor substrate (11).

In the first step, a first tape reinforcing member (11) is adhered tothe other surface of the prepared semiconductor substrate (11) with anorganic adhesive and one surface of the semiconductor substrate (11) maybe thinly processed, thereby thinning the semiconductor substrate (11)up to a predetermined thickness; and in the second step, thesemiconductor substrate (11) may be fixed onto a stage (24) having aheater, the semiconductor substrate (11) fixed onto the stage (24) maybe heated, thereby reducing warpage caused on the semiconductorsubstrate (11) by a difference between a coefficient of linear expansionof the first tape reinforcing member (12) and a coefficient of linearexpansion of the semiconductor substrate (11).

Furthermore, in order to solve the aforementioned problem, a ring-shapedreinforcing member according to a second aspect of the present inventionis used in a manufacturing process of a semiconductor device having asemiconductor substrate (11) thinned to a predetermined thickness. Thereinforcing member has an opening at its center, and has a ring shapewith an outer diameter equal to an outer diameter of the semiconductorsubstrate (11), and is adhered to one surface of the semiconductorsubstrate (11) with an adhering material, thereby enhancing strength ofthe semiconductor substrate (11) reduced by thinly processing.

The ring-shaped reinforcing member is adhered to the semiconductorsubstrate with the adhering material formed of, for example, aninorganic adhesive and polyimide resin, thereby enhancing strength ofthe semiconductor substrate reduced by thinly processing. Moreover,since the ring-shaped reinforcing member is adhered to the semiconductorsubstrate with, for example, the inorganic adhesive and polyimide resin,no gas is generated under processing conditions for forming an electrodeon one or the other surface of the semiconductor substrate. Furthermore,since the ring-shaped reinforcing member has the same outer diameter asthat of the semiconductor substrate, there is no need of changing theexisting transferring unit and the like to be suitable for the dedicatedjig, unlike the case in which the semiconductor substrate is held by thededicated jig. Accordingly, it is possible to prevent occurrence of thenick and the crack on the thinly processed semiconductor substratewithout largely changing the manufacturing unit and increasingmanufacturing cost.

The ring-shaped reinforcing member may have a thickness larger than apredetermined thickness of the thinly processed semiconductor device.

The ring-shaped reinforcing member may be formed of the same material asthat of the semiconductor substrate (11) and have a coefficient oflinear expansion equal to that of the semiconductor substrate (11).

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1J are side views each illustrating a semiconductor devicemanufacturing method according to a first embodiment of the presentinvention;

FIG. 2 is a perspective view illustrating a state that a reinforcingring is adhered to a semiconductor substrate;

FIGS. 3A to 3G are side views each illustrating a semiconductor devicemanufacturing method according to a second embodiment of the presentinvention; and

FIGS. 4A to 4E are side views each illustrating a conventionalsemiconductor device manufacturing method.

BEST MODE FOR CARRYING OUT THE INVENTION

A semiconductor device manufacturing method and a ring-shapedreinforcing member used therein according to embodiments of the presentinvention will be described below with reference to the drawings. Thefollowing explains a case in which a power transistor is manufactured asan example.

First Embodiment

An explanation is given of a semiconductor device manufacturing methodand a ring-shaped reinforcing member used therein according to thisembodiment with reference to FIGS. 1A to 1G and FIG. 2.

First of all, a semiconductor substrate (semiconductor wafer) 11 isprepared as illustrated in FIG. 1A. The semiconductor substrate 11 isformed of for example, a single crystal silicon, and has a substantiallycircular shape with a size of, for example, a thickness of 500 μm and adiameter of 15 mm (6 inches). In a surface region of one surface of thesemiconductor substrate 11, multiple semiconductor regions (not shown)for forming multiple semiconductor devices are formed by impuritydiffusion and the like. Moreover, on one surface of the semiconductorsubstrate 11, a metallic film (not shown) is formed by sputtering,vacuum deposition, etc. The metallic film forms one end of the electrodeof the semiconductor device, for example, an emitter electrode and abase electrode of the power transistor.

Next, a first tape member 12 is adhered to one surface of thesemiconductor substrate 11 with an ultraviolet curable adhesive, alow-tack adhesive, and an organic adhesive such as thermoplastic resin.The first tape member 12 is formed of resin with high heat resistant,for example, polyethylene terephthalate resin, vinyl chloride resin, andpolyolefin resin. The first tape member 12 protects one surface of thesemiconductor substrate 11 and prevents occurrence of the nick and thecrack on the semiconductor substrate 11 at the time of thinning thesemiconductor substrate 11 in a next process.

Next, a portion (broken line portion in the figure) of the semiconductorsubstrate 11 that is close to the other surface of the semiconductorsubstrate 11 is removed by back grinding (cutting process) and chemicaletching to thin the semiconductor substrate 11 as illustrated in FIG.1B. For example, a semiconductor substrate with an original thickness of500 μm is thinned up to 100 μm. Since the semiconductor substrate 11 isreinforced by the first tape member 12 adhered to one surface,occurrence of the nick and he crack by a mechanical stress generated atthe time of the thinning process is restrained or prevented.

Sequentially, a reinforcing ring 13 is adhered to the other surface ofthe semiconductor substrate 11 as illustrated in FIG. 1C. Thereinforcing ring 13 includes he same material as that (for example,single crystal silicon) of the semiconductor substrate 11 and is formedby cutting a central portion of a disk-like silicon substratecircularly.

FIG. 2 illustrates a state in which the reinforcing ring 13 is adheredto the semiconductor substrate 11. As illustrated in the figure, anouter diameter of the reinforcing member 13 is set to the same as thatof the semiconductor substrate 11. The reinforcing member 13 is adheredto an outer periphery of the semiconductor substrate 11. In this state,the other surface of the semiconductor substrate 11 is exposed as aregion for electrode via the central portion (circularly cut portion) ofthe reinforcing member 13. For example, the reinforcing member 13 has awidth of 5 to 7 mm and a thickness of about 400 to 900 μm and is formedto have a size and a shape such that strength of the semiconductorsubstrate 11 is sufficiently obtained and the region for electrode canbe sufficiently exposed. Additionally, the thickness of the reinforcingring 13 may be preferably set to a value larger than the thickness ofthe thinned semiconductor substrate 11 among the semiconductorsubstrates 11. More preferably, the reinforcing member 13 may be formedin such a way that a thickness obtained by combining the thinnedsemiconductor substrate 11 with the reinforcing ring 13 is substantiallythe same as a thickness obtained by combining the non-thinnedsemiconductor substrate 11 with the tape member 12. In this embodiment,the semiconductor substrate 11 is cut by 400 μm and the reinforcing ring13 has a thickness of about 600 μm.

The reinforcing ring 13 is adhered to the semiconductor substrate 11with an inorganic adhering material layer 14. The inorganic adheringmaterial layer 14 is formed of, for example, material that forms thesemiconductor substrate 11, namely, an inorganic material with a goodadhesive property to silicon. Moreover, the inorganic material 14 has amelting point, which is lower than heat resistance temperature of thefirst tape member 12 and higher than temperature (for example, 100° C.to 200° C.) at which sputtering and vacuum deposition processes to bedescribed later are executed.

As the inorganic material that meets such a condition, for example,metals such as indium (melting point of 156.6° C.), tin (melting pointof 232° C.), bismuth (melting point of 271.4° C.), etc., or an alloy ofthese are cited. The inorganic material is selected according totemperature at which sputtering and vacuum deposition processes areexecuted and the heat resistance temperature of the first tape member12.

For example, a melting point (liquid phase temperature) of an alloyformed of tin of 42% and bismuth of 58% is 138.5° C., a melting point(liquid phase temperature) of an alloy formed of lead of 44.5% andbismuth of 45.5% is 124° C., a melting point (liquid phase temperature)of an alloy formed of tin of 60% and bismuth of 40% is 170° C., amelting point (liquid phase temperature) of an alloy formed of indium of52% and tin of 48% is 117° C., and a melting point (liquid phasetemperature) of an alloy formed of indium of 50% and tin of 50% is 127°C.

Specifically, adhesion of the reinforcing ring 13 to the semiconductorsubstrate 11 using the inorganic adhering material layer 14 as mentionedabove can be executed by the following way.

First of all, the inorganic adhering material layer 14 is formed on onesurface of the reinforcing ring 13 by plating. The inorganic adheringmaterial layer 14 is formed on one surface of the reinforcing ring 13entirely or scattered thereon in such a way that the semiconductorsubstrate 11 and the reinforcing ring 13 are sufficiently adhered toeach other.

Next, one surface of the reinforcing ring 13 on which the inorganicadhering material layer 14 is formed is placed on the other surface ofthe semiconductor substrate 11. Sequentially, the result is heated attemperature at which the inorganic adhering material layer 14 is melted(temperature more than the melting point of the metal or alloy thatforms the inorganic adhering material layer 14). Then, the result iscooled to cure the inorganic adhering material layer 14, so that thereinforcing ring 13 is adhered to the semiconductor substrate 11.

As mentioned above, the melting point of the metal or alloy that formsthe inorganic adhering material layer 14 is lower than the heatresistance temperature of the first tape member 12. This prevents thefirst tape member 12 from deteriorating by the heat at the time ofheating and melting the inorganic adhering material layer 14.

After adhesion of the reinforcing ring 13, the first tape member 12 ispeeled and removed from one surface of the semiconductor substrate 11 asillustrated in FIG. 11D. For example, in the case where the first tapemember 12 is adhered to the semiconductor substrate 11 with the organicadhesion formed of ultraviolet curable resin, the adhesive is irradiatedwith an ultraviolet ray. This causes a polymerization reaction to reduceadhesive strength of the adhesive, so that the first tape member 12 canbe easily peeled from the semiconductor substrate 11.

Next, in order to form a metallic film (electrode) on the other surfaceof the semiconductor substrate 11, the semiconductor substrate 11 istransferred to a metallic film forming unit. Additionally, since thereinforcing ring 13 is adhered to the semiconductor substrate 11 at thetransferring time, strength of the semiconductor substrate 11 issufficiently ensured and occurrence of the nick and the crack isrestrained or prevented.

Moreover, as mentioned above, the total thickness of the semiconductorsubstrate 11 for example, 100 μm) and the reinforcing ring 13 (forexample, 600 μm) is substantially he same as the thickness of theoriginal semiconductor substrate 11 which is not thinned. This makes itpossible to transfer the semiconductor substrate 11 and the reinforcingring 13 using the existing transferring apparatus for transferring theconventional non-thinned semiconductor substrate 11.

After transferring, a metallic film 15 is formed on the other surface ofthe semiconductor substrate 11 by sputtering, vacuum deposition, etc.,as illustrated in FIG. 1E. The metallic film 15 is formed of, forexample, titanium, nickel, gold, platinum, etc. and has a thickness of,for example, 0.5 μm. The metallic film 15 forms, for example, acollector electrode of a power transistor. The metallic film 15 isformed on not only the other surface of the semiconductor substrate 11but also the upper surface of the reinforcing ring 13.

At the time of forming the metallic film 15, the reinforcing ring 13 isadhered to the other surface of the semiconductor substrate 11 with theinorganic adhering material layer 14. The inorganic adhering materiallayer 14 is formed of the metal or alloy whose melting point is higherthan processing temperature for sputtering, vacuum deposition, etc. asmentioned above. Accordingly, the inorganic adhering material layer 14does not change its state or generate gas under conditions for formingthe metallic film 15, for example, processing temperature of 100° C. to200° C. and vacuum density of about 10⁻⁵ Pa (10⁻⁷ Torr), unlike theorganic adhesive.

Since the inorganic adhering material layer 14 is not melted by heat atthe film forming time, the semiconductor substrate 11 can maintain thestate in which the semiconductor substrate 11 is surely held by thereinforcing ring 13.

In this way, the reinforcing ring 13 is adhered to the semiconductorsubstrate 11 with the adhering material formed of an inorganic material,thereby making it possible to form the metallic film 15 with highreliability without an adverse influence.

After forming the metallic film 15, the metallic film 15 is patterned toform an electrode as required.

Sequentially, the semiconductor substrate 11 is transferred to the otherprocessing unit. At the time of transferring, the semiconductorsubstrate 11 is also reinforced by the reinforcing ring 13 and asufficient thickness is given thereto by the reinforcing ring 13, herebymaking it possible to transfer the semiconductor substrate 11 using theexisting ransferring apparatus for transferring the conventionalnon-thinned semiconductor substrate 11.

A convex stage (susceptor) 16 for mounting the semiconductor substrate11 thereon is provided on the processing unit as illustrated in FIG 1F.An upper surface of a convex portion of the stage 16 is formed to have aflat surface with a diameter smaller than an inner diameter of thereinforcing ring 13. On the flat surface, the semiconductor substrate 11whose surface (other surface) to which the reinforcing ring 13 isadhered is directed downward is mounted. Accordingly, the metallic film15 formed on the other surface of the semiconductor substrate 11 and theflat surface come in contact with each other.

In the convex portion of the stage 16, at least a portion contacting themetallic film 15 is formed of metal and connected to a checking circuit30. The checking circuit 30 is also connected to a probe 17 provided inthe processing unit. The probe 17 comes in contact with the electrodeformed on one surface of the semiconductor substrate 11 to makedistinction between a non-defective item and a defective item by inkmarking, mapping, etc.

Next, a second tape member 18 is adhered to one surface of thesemiconductor substrate 11 using the organic adhesive (not shown) asillustrated in FIG. 1G The second tape member 18 is formed of resinmaterial having a heat resistance temperature higher than the meltingpoint of the inorganic adhering material layer 14, similar to the firsttape member 12.

Sequentially, the semiconductor substrate 11 is heated at temperaturemore than the melting temperature of the inorganic adhering materiallayer 14 in a state that the second tape member 18 is adhered to onesurface and the reinforcing ring 13 is adhered to the other surface,respectively. As a result, the inorganic adhering material layer 14 ismelted and the reinforcing ring 13 is removed from the semiconductorsubstrate 11 as illustrated in FIG. 1H. Since the heat resistancetemperature of the second tape member 18 is higher than the meltingpoint of the inorganic adhering material layer 14, no deteriorationoccurs when the reinforcing ring 13 is removed.

Since the second tape member 18 is adhered to one main surface of thesemiconductor substrate 11, strength of the semiconductor substrate 11is sufficiently maintained even after the reinforcing ring 13 isremoved. Additionally, in this state, the inorganic material remains onthe other surface of the semiconductor substrate 11 and is adheredthereto.

Next, a dicing tape 19 is adhered to the other surface of thesemiconductor substrate 11 as illustrated in FIG. 1I. The dicing tape 19is formed of polyvinyl chloride, polyester, and the like. The dicingtape 19 is held by a ring-shape carrier member 20 provided on the outerperiphery.

Sequentially, the second tape member 18 is removed from thesemiconductor substrate 11. In the case where the second tape member 18is adhered to one surface of the semiconductor substrate 11 with theultraviolet curable adhesive, the second tape member 18 is removed bybeing irradiated with the ultraviolet ray.

Next, the semiconductor substrate 11 is mounted on a dicing stage 23 insuch a way hat the dicing tape 19 comes in contact with the uppersurface of the dicing stage 23 as illustrated in FIG. 1J. The dicingstage 23 is formed of, for example, porous material. The semiconductorsubstrate 11 mounted on the dicing stage 23 is fixed to the uppersurface of the dicing stage 23 by suction from the downward of thedicing stage 23.

Next, the semiconductor substrate 11 is diced by a dicing cutter 21.Accordingly, he respective semiconductor devices (dies) 22 are separatedfrom the semiconductor substrate 11. Since the dicing tape 19 is adheredto the semiconductor substrate 11 with, for example, the ultravioletcurable adhesive, irradiation of the ultraviolet ray is applied in orderto peel the dicing tape 19 from each die 22. Then, each die 22 is pickedup by a suction jig, which is called a collet, and transferred to a unitfor executing a next process such as a die boding and the like.

As mentioned above, according to the present embodiment, in thesemiconductor device manufacturing method using the relatively thinsemiconductor substrate 11, the reinforcing ring 13 formed of silicon isadhered to the semiconductor substrate 11 with the inorganic adheringmaterial layer 14 formed of the metal or alloy, so that the metallicfilm 15 is formed.

The above-structured reinforcing ring 13 and inorganic adhering materiallayer 14 are used, so that the electrode can be formed by sputtering,vacuum deposition, etc. without adhering the tape member to thesemiconductor substrate 11 with the organic adhesion for reinforcement.This makes it possible to form the electrode (metallic film 15) in astate that no gas is generated from the organic adhesive and tomanufacture the semiconductor device with high reliability. Moreover, itis possible to maintain the state in which the thinned semiconductorsubstrate 11 is held by the reinforcing ring 13 without melting theinorganic adhesion layer 14 at the film forming time. For this reason,occurrence of the nick and the crack in semiconductor substrate 11 isprevented.

Furthermore, the inorganic adhering material layer 14 is formed of themetal or alloy having the melting point lower than the heat resistancetemperature of the first tape member 12. For this reason, it is possibleto adhere the reinforcing ring 13 to the semiconductor substrate 11 bymelting the inorganic adhering material layer 14 in a state that thefirst tape member 12 is adhered to the semiconductor substrate 11,without degrading the first tape member 12.

Moreover, a total thickness of the thinned semiconductor substrate 11and the reinforcing ring 13 is substantially the same as the thicknessof the original semiconductor device, which is not thinly processed. Forthis reason, the existing transferring apparatus can be used as it is.Accordingly, the use of the reinforcing ring 13 of this embodiment makesit possible to prevent occurrence of the nick and the crack on the thinsemiconductor substrate 11 without largely increasing manufacturingcost.

Second Embodiment

This embodiment explains a semiconductor device manufacturing methodwhen the reinforcing ring 13 is adhered to the semiconductor substrate11 with heat resistance resin, which is formed of polyimide, in place ofthe inorganic adhering material layer 14. The semiconductor devicemanufacturing method of this embodiment will be explained below withreference to FIGS. 3A to 3G.

First of all, the semiconductor substrate 11 is prepared. Similar to thefirst embodiment, multiple semiconductor devices are formed on thesemiconductor substrate 11. Moreover, electrodes are formed on onesurface of the semiconductor substrate 11.

Next, the first tape member 12 is adhered to one surface of thesemiconductor substrate 11 with, for example, an ultraviolet curableadhesive and the semiconductor substrate 11 is thinned. Even in thisembodiment, the semiconductor substrate 11 with an original thickness of500 μm is thinned up to 100 μm.

Sequentially, the semiconductor substrate 11 is mounted on an absorptionstage 24 in a state that the other surface to which the first tapemember 12 is adhered is directed upwardly as illustrated in FIG. 3A. Theabsorption stage 24 is formed of, for example, porous material. Thesemiconductor substrate 11 is fixed onto the absorption stage 24 bysuction from the downward of the absorption stage 24.

The absorption stage 24 includes a heater 31, sets temperature of anabsorption surface (surface on which the semiconductor substrate 11 ismounted) to be higher than a room temperature by about 5 to 70° C., andheats the semiconductor substrate 11. The absorption stage 24 heats themounted semiconductor substrate 11 to temperature (for example, 40 to70° C.), which is higher than the room temperature by several tens ofdegrees Celsius.

There is a case in which warpage occurs on the semiconductor substrate11 to which the first tape member 12 is adhered by a difference in acoefficient of linear expansion between the semiconductor substrate 11and the first tape member 12. The warpage is reduced by heating by theabsorption stage 24.

To explain more specifically, the first tape member 12 is adhered to onesurface of the semiconductor substrate 11 in a state that thesemiconductor substrate 11 is heated to a predetermined temperature. Forthis reason, when the temperature of the semiconductor substrate 11decreases, warpage occurs on the semiconductor substrate 11 by thedifference in the coefficient of linear expansion in some cases. Forthis reason, the semiconductor substrate 11 to which the first tapemember 12 is adhered is heated again on the absorption stage 24 toreduce warpage caused by the difference in the coefficient of linearexpansion. This makes it possible to execute the processing in thefollowing various processes with high accuracy.

Next, the first tape member 12 is removed from the semiconductorsubstrate 11 fixed onto the absorption stage 24.

Subsequently, the same reinforcing ring 13 as that of the firstembodiment is prepared and adhered to the semiconductor substrate 11with the heat resistance adhering material layer 25 as illustrated inFIG. 3C.

The heat resistance adhering material layer 25 is formed of, forexample, polyimide resin. The heat resistance adhering material layer 25has a melting point or softening point, which is higher than temperature(for example, 100 to 200° C.) at which sputtering and vacuum depositionprocesses to be described later are executed.

Specifically, adhesion of the reinforcing ring 13 to the semiconductorsubstrate 11 using the heat resistance adhering material layer 25 can beexecuted by the following way.

First of all, for example, melted or softened heat resistance adheringmaterial is applied onto one surface of the reinforcing ring 13 to forma heat resistance adhering material layer 25.

Next, the reinforcing ring 13 is mounted on the semiconductor substrate11 in such a way that one surface of the reinforcing ring 13 and onesurface of the semiconductor substrate 11 are opposed to each other. Thesemiconductor substrate 11, the reinforcing ring 13 and the heatresistance adhering material layer 25 are heated at temperature which ishigher than temperature at which sputtering and vacuum depositionprocesses to be described later are executed, and the heat resistanceadhering material layer 25 is melted or softened again.

Then, the semiconductor substrate 11, the reinforcing ring 13 and theheat resistance adhering material layer 25 are cooled to adhere thereinforcing ring 13 to the semiconductor substrate 11.

Adhesion of the reinforcing ring 13 is executed after peeling the firsttape member 12 from the semiconductor substrate 11. However, since thesemiconductor substrate 11 is fixed onto the absorption stage 24,strength of the semiconductor substrate 11 is sufficiently ensured. Thisrestrains or prevents occurrence of the nick and the crack insemiconductor substrate 11 at the time of adhering the reinforcing ring13.

After adhering the reinforcing ring 13, the semiconductor substrate 11is transferred to a metallic film forming unit for forming a metallicfilm. At the transferring time, since the reinforcing ring 13 is adheredto the semiconductor substrate 11, strength of the semiconductorsubstrate 11 is sufficiently ensured to restrain or prevent occurrenceof the nick and the crack.

The total thickness of the semiconductor substrate 11 and thereinforcing ring 13 is substantially the same as the thickness of thenon-thinned semiconductor substrate 11. For this reason, it is possibleto transfer the semiconductor substrate 11 and the reinforcing ring 13using the existing transferring apparatus for transferring theconventional non-thinned semiconductor substrate 11.

After transferring the semiconductor substrate 11 to the metallic filmforming unit, the metallic film 15 is formed on the other surface of thesemiconductor substrate 11 by sputtering, vacuum deposition, etc., asillustrated in FIG. 3D. The metallic film 15 is formed of, for example,titanium, nickel, gold, platinum, etc. and has a thickness of, forexample, 0.5 μm.

At the time of forming the metallic film 15, the reinforcing ring 13 isadhered to the semiconductor substrate 11 with the heat resistanceadhering material layer 25 formed of polyimide resin. As mentionedabove, since the heat resistance adhering material layer has a meltingpoint or a softening point which is higher than temperature at whichsputtering and vacuum deposition processes are executed, no gas isgenerated by decomposition under electrode forming conditions ofprocessing temperature, namely, 100° C. to 200° C. and vacuum density ofabout 10⁻⁵ Pa (10⁻⁷ Torr).

In this way, the reinforcing ring 13 is adhered to the semiconductorsubstrate 11 with the adhering material formed of polyimide resin,thereby making it possible to form the metallic film 15 without anadverse influence.

After forming the metallic film 15, the metallic film 15 is patterned asrequired to form, for example, a collector electrode of the powertransistor.

Sequentially, the semiconductor substrate 11 is transferred to the otherprocessing unit. At the time of transferring, the semiconductorsubstrate 1, which is stably held by the reinforcing ring 13, can betransferred by the existing transferring apparatus.

A stage 26 with a flat plane is provided in the processing unit asillustrated FIG. 3E. The transferred semiconductor substrate 11 ismounted on the flat surface of the stage 26. As illustrated, since thesemiconductor substrate 11 is mounted on the stage 26 in a state thatthe surface to which the reinforcing ring 13 is attached is directedupwardly, the stage 26 does not have to have a convex shape, unlike thestage 16 of the first embodiment.

At least a portion of the stage 26 coming in contact with thesemiconductor substrate 11 is formed of metal and connected to thechecking circuit 30. The checking circuit 30 is also connected to aprobe 27 provided in the processing unit. Checking is executed by theprobe 27, similar to the first embodiment.

After checking, the dicing tape 19 is adhered to the other surface ofthe semiconductor substrate 11, similar to the first embodiment, asillustrated in FIG. 3F. The dicing tape 19 is formed of polyvinylchloride, polyester, and the like. The dicing tape 19 is held by thering carrier member 20 provided along the outer periphery.

Next, the semiconductor 11 is mounted on the dicing stage 23 asillustrated in FIG. 3G. More specifically, the semiconductor 11 ismounted on the dicing stage 23 in such a way that the dicing tape 19adhered to the other surface of the semiconductor substrate 11 comes incontact with the upper surface of the dicing stage 23. The semiconductorsubstrate 11 mounted on the dicing stage 23 is fixed onto the uppersurface of the dicing stage 23 by suction from the downward of thedicing stage 23.

Then, similar to the first embodiment, the semiconductor substrate 11 isdiced by the dicing cutter 21 in a state that it is fixed onto thedicing stage 23.

The dicing tape 19 is peeled from each of the semiconductor devices(dies) 22 separated by dicing, similar to the first embodiment. Then,each die 22 is picked up by a suction jig, which is called a collet, andtransferred to a unit for executing a next process (for example, dieboding).

Additionally, the portion of the semiconductor substrate 11 to which thereinforcing ring 13 is adhered is not used as the die 22, it is removedin a state that the reinforcing ring 13 is adhered as it is.

As mentioned above, even if the heat resistance adhering material layer25 formed of polyimide resin is used to adhere the reinforcing ring 13to the semiconductor substrate 11, the same effect as that of the firstembodiment can be obtained.

Moreover, in the manufacturing method of this embodiment, after thefirst tape member 12 is peeled from the semiconductor substrate 11, thereinforcing ring 13 is adhered to the semiconductor substrate 11. Forthis reason, there is no need of considering heat resistance of thefirst tape member 12 at the time of fixing the reinforcing ring 13. As aresult, flexibility in selecting the material to be used as the firsttape member 12 is increased as compared with the first embodiment andcost reduction can be obtained.

Furthermore, in the manufacturing method of this embodiment, since thethinly processed semiconductor substrate 11 is heated, it is possible toreduce warpage caused by the difference in the coefficient of linearexpansion between the semiconductor substrate 11 and the first tapemember 12.

According to the manufacturing method of this embodiment, the number ofprocesses to remount the tape member is reduced as compared with themanufacturing method of the first embodiment, so that higherproductivity can be realized.

Additionally, the manufacturing methods of the first and secondembodiments can be executed by causing a computer to control thetransferring unit, semiconductor processing unit and the like based on aprogram.

The present invention is not limited to the aforementioned embodiments.For example, the manufacturing methods of the first and secondembodiments may be appropriately combined. For example, in the firstembodiment, the heat resistance adhering material layer 25 may be usedin place of the inorganic adhering material layer 14, and in the secondembodiment, the inorganic adhering material layer 14 may be used inplace of the heat resistance adhering material layer 25.

In the first and second embodiments, the explanation is given of thecase in which the reinforcing ring 13 is formed of the same material asthat of the semiconductor substrate 11 as an example. The use of such astructure makes it possible to set the coefficient of linear expansionof the semiconductor substrate 11 and that of the reinforcing ring 13 tobe the same and to reduce or prevent strain caused by the difference inthe coefficient of linear expansion. However, as long as generation ofstrain caused by the difference in the coefficient of linear expansioncan be reduced or prevented, the reinforcing ring 13 may be formed ofother materials.

In the first and second embodiments, the explanation is given of thecase in which the semiconductor substrate 11 is formed of a singlecrystal silicon substrate as an example. However, the semiconductorsubstrate 11 may be formed of a compound semiconductor such as indiumphosphide, silicon carbide, etc.

In the first and second embodiments, the explanation is given of thecase in which the power semiconductor device is manufactured as anexample. However, the present invention is not limited to this, and theother type of semiconductor device using a relative thin semiconductorsubstrate may be manufactured.

This application is based on Japanese Patent Application No. 2002-183939filed on Jun. 25, 2002 and Japanese Patent Application No. 2002-319884filed on Nov. 1, 2002, specification, claims and drawings of which areincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The present invention can be used in the method for manufacturing thesemiconductor device including a relatively thin semiconductorsubstrate.

1. A semiconductor device manufacturing method comprising: a first stepof preparing a semiconductor substrate (11) on which multiplesemiconductor devices are formed and thinning the semiconductorsubstrate (11); a second step of adhering a reinforcing member (13)through which a part of one surface of the semiconductor substrate (11)is exposed to the one surface thereof with an adhering material; a thirdstep of forming a metallic film (15) for forming an electrode providedin the semiconductor device on an exposed portion of one surface of thesemiconductor substrate (11) or the other surface of the semiconductorsubstrate (11); and a fourth step of removing the reinforcing member(13) from the semiconductor substrate (11) and dicing the semiconductorsubstrate (11); and wherein the adhering member (13, 25) is formed ofmaterial which changes its state at temperature higher than a processingtemperature in the third step.
 2. The semiconductor device manufacturingmethod according to claim 1, wherein the reinforcing member (13) has anopening at its center and a ring shape with an outer diameter equal toan outer diameter of the semiconductor substrate (11); wherein thesecond step combines an outer periphery of the semiconductor substrate(11) with an outer periphery of the ring-shaped reinforcing member (13)to adhere the reinforcing member (13) to one surface of thesemiconductor substrate (11) with the adhering material; and wherein thethird step forms the metallic film (15) on exposed one surface of thesemiconductor substrate (11) through the opening of the ring-shapedreinforcing member (13).
 3. The semiconductor device manufacturingmethod according to claim 1, wherein the adhering material is formed ofa metal or alloy having a melting point higher than a processingtemperature in the third step or heat resistance resin having a meltingpoint or a softening point higher than the processing temperature in thethird step.
 4. The semiconductor device manufacturing method accordingto claim 3, wherein the heat resistance resin is polyimide resin.
 5. Thesemiconductor device manufacturing method according to claim 3, whereinin the second step, the adhering material layer (14, 25) is formed onone surface of the ring-shaped reinforcing member (13), one surface ofthe ring-shaped reinforcing member (13) is placed on one surface of thesemiconductor substrate (11) and the adhering material layer (14, 25)disposed between the ring-shaped reinforcing member (13) and thesemiconductor substrate (11) is melted by heating, and the adheringmaterial layer (14, 25) is hardened by cooling to adhere the ring-shapedreinforcing member (13) to the semiconductor substrate (11).
 6. Thesemiconductor device manufacturing method according to claim 5, whereinin the first step, a first tape reinforcing member (12) is adhered tothe other surface of the prepared semiconductor substrate (11) with anorganic adhesive and one surface of the semiconductor substrate (11) isthinly processed in a state that the first tape reinforcing member (12)is adhered, thereby thinning the semiconductor substrate (11) up to apredetermined thickness; wherein in the second step, the ring-shapedreinforcing member (13) is adhered to one surface of the semiconductorsubstrate with the adhering material layer (14) in a state that thefirst tape reinforcing member (12) is adhered to the other surface ofthe semiconductor substrate (11); and wherein in the third step, themetallic film (15) is formed on one surface of the semiconductorsubstrate (11) through the opening of the ring-shaped reinforcing member(13) after removing the first reinforcing member (12) from thesemiconductor substrate (11) in a state that the ring-shaped reinforcingmember (13) is adhered to the semiconductor substrate (11).
 7. Thesemiconductor device manufacturing method according to claim 6, whereinthe adhering material layer (14) has a melting point lower than heatresistance temperature of the first tape member (12).
 8. Thesemiconductor device manufacturing method according to claim 6, whereinin the fourth step, a second tape reinforcing member (18) is adhered tothe other surface of the semiconductor substrate (11), the ring-shapedreinforcing member (13) is removed from one surface of the semiconductorsubstrate (11), and the semiconductor substrate (11) is diced into chips(22) that form the respective semiconductor devices.
 9. Thesemiconductor device manufacturing method according to claim 8, whereinthe adhering material layer (14) has a melting point lower than heatresistance temperature of the second tape reinforcing member (18); andthe adhering material layer (14) is melted by heating at temperaturelower than heat resistance temperature of the second tape reinforcingmember (18), thereby removing the ring-shaped reinforcing member (13)from the semiconductor substrate (11).
 10. The semiconductor devicemanufacturing method according to claim 3, wherein in the first step, afirst tape reinforcing member (12) is adhered to the other surface ofthe prepared semiconductor substrate (11) with an organic adhesive andone surface of the semiconductor substrate (11) is thinly processed,thereby thinning the semiconductor substrate (11) up to a predeterminedthickness; and wherein in the second step, the semiconductor substrate(11) is fixed onto a stage (24) having a heater and the semiconductorsubstrate (11) fixed onto the stage (24) is heated, thereby warpagecaused on the semiconductor substrate (11) by a difference between acoefficient of linear expansion of the first tape reinforcing member(12) and a coefficient of linear expansion of the semiconductorsubstrate (11) is reduced.
 11. A ring-shaped reinforcing member, whichis used in a manufacturing process of a semiconductor device having asemiconductor substrate (11) thinly processed to a predeterminedthickness, said reinforcing member having an opening at its center,having a ring shape with an outer diameter equal to an outer diameter ofthe semiconductor substrate (11), and being adhered to one surface ofthe semiconductor substrate (11) with an adhering material, therebyenhancing strength of the semiconductor substrate (11) reduced by thinlyprocessing.
 12. The ring-shaped reinforcing member according to claim11, wherein the ring-shaped reinforcing member has a thickness largerthan a predetermined thickness of the thinly processed semiconductordevice.
 13. The ring-shaped reinforcing member according to claim 12,wherein the ring-shaped reinforcing member is formed of the samematerial as that of the semiconductor substrate (11) and has acoefficient of linear expansion equal to that of the semiconductorsubstrate (11).